Question

 If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of 
A. `CuSO_(4)`
B. `CuCO_(3)`
C. `Cu(NO_(3))_(2)`
D. CuO

Answer 1

Correct Answer - b
Copper reacts with `CO_(2)` present in air and forms a green coating on its Surface due to the formation of basic copper carbonate `[CuCO_(3).Cu(OH)_(2)]` as
`2Cu+underset("From air")(O_(2))+CO_(2)+H_(2)Oto underset("Basic copper carbonate(green coating)")(CuCO_(3).Cu(OH)_(2))`